Power save with end of data indication

ABSTRACT

A particular method includes receiving a first frame from a station at an access point indicating that the station is to enter a power save mode. The method also includes transmitting one or more data frames from the access point to the station. The one or more data frames were buffered for transmission prior to receipt of the first frame. The method further includes transmitting an end of data frame to the station. Another particular method includes transmitting a first frame from the station to the access point indicating that the station is to enter the power save mode. The method also includes refraining from entering the power save mode until an end of data frame is received from the access point.

I. CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of and claimspriority to commonly owned patent application Ser. No. 13/566,908 filedAug. 3, 2012, which claims priority from commonly owned U.S. ProvisionalPatent Application No. 61/529,796 filed Aug. 31, 2011 and U.S.Provisional Patent Application No. 61/533,560 filed Sep. 12, 2011, thecontents of which are expressly incorporated herein by reference intheir entirety.

II. FIELD

The present disclosure is generally related to power savings whileretrieving buffered data from an access point.

III. DESCRIPTION OF RELATED ART

Advances in technology have resulted in smaller and more powerfulcomputing devices. For example, there currently exist a variety ofportable personal computing devices, including wireless computingdevices, such as portable wireless telephones, personal digitalassistants (PDAs), and paging devices that are small, lightweight, andeasily carried by users. More specifically, portable wirelesstelephones, such as cellular telephones and internet protocol (IP)telephones, can communicate voice and data packets over wirelessnetworks. Further, many such wireless telephones include other types ofdevices that are incorporated therein. For example, a wireless telephonecan also include a digital still camera, a digital video camera, adigital recorder, and an audio file player. Also, such wirelesstelephones can process executable instructions, including softwareapplications, such as a web browser application, that can be used toaccess the Internet. As such, these wireless telephones can includesignificant computing capabilities.

Such devices may be configured to communicate data via a wirelessnetwork. For example, many devices are configured to operate accordingto an Institute of Electrical and Electronics Engineers (IEEE) 802.11specification that enables wireless exchange of data via an accesspoint. Many communication devices are configured to enter a power savemode, during which time the communication device may shut down one ormore components, thereby conserving power. While utilization of thispower save mode may provide power conservation, problems may arise indetermining when the communication device should resume normal operationand/or when the communication device should enter the power save mode.

IV. SUMMARY

In particular embodiment, a method includes receiving a power savepolling (PS-Poll) frame from a station at an access point. The methodalso includes, in response to receiving the power save polling frame,transmitting a frame from the access point to the station indicatingwhether traffic associated with the station is buffered at the accesspoint. For example, the frame may include an acknowledgement (ACK)transmitted a short interframe space (SIFS) after receipt of the powersave polling frame. A particular bit (e.g., a more data (MD) bit) in amedia access control (MAC) header of the frame may be used to indicatewhether or not buffered traffic is pending.

In another particular embodiment, a method includes transmitting a powersave polling frame from a station to an access point. The method alsoincludes, in response to transmitting the power save polling frame,receiving a frame from the access point indicating whether trafficassociated with the station is buffered at the access point.

In another particular embodiment, a method includes receiving a firstframe from a station at an access point, the first frame indicating thatthe station is to enter a power save mode. The method also includestransmitting one or more data frames from the access point to thestation, where the one or more data frames were buffered fortransmission prior to receipt of the first frame. The method furtherincludes transmitting an end of data frame to the station.

In another particular embodiment, a method includes transmitting a firstframe from a station to an access point indicating that the station isto enter a power save mode. The method also includes refraining fromentering the power save mode until an end of data frame is received fromthe access point. The method further includes entering the power savemode at the station in response to receiving the end of data frame fromthe access point. For example, the end of data frame may be an end ofdata indication (EODI). Alternately, the end of data frame may be aframe that includes a MAC header having an asserted end of serviceperiod (EOSP) bit.

In another particular embodiment, a method includes receiving a fetchtrigger frame from a station at an access point. The method alsoincludes fetching one or more data frames associated with the station inresponse to the fetch trigger frame. The method further includesrefraining from transmitting the one or more fetched data frames to thestation until a delivery condition associated with the station issatisfied. For example, the delivery condition may be satisfied when theaccess point determines that a predetermined fetch time has elapsed orthat a delivery trigger frame has been received from the station. Thepredetermined fetch time may be indicated by the station in the fetchtrigger frame or may be indicated by the access point in an ACK responseto the fetch trigger frame. During the fetch time, the station may entera power saving (e.g., low power) state. The access point may communicatewith one or more other stations during the fetch time.

In another particular embodiment, a method includes transmitting a fetchtrigger frame from a station to an access point. The method alsoincludes entering a power save mode at the station until a determinationat the station that a fetch time associated with the station haselapsed, where the access point is configured to communicate with one ormore other stations during the fetch time. The method further includesin response to the determination, exiting the power save mode andreceiving one or more data frames from the access point at the stationafter exiting the power save mode.

One particular advantage provided by at least one of the disclosedembodiments is reduced power consumption and increased signalingefficiency between stations and access points in a wireless network. Forexample, the disclosed embodiments may enable stations to remain in apower save state for a predetermined fetch time. As another example, thedisclosed embodiments may enable transmission of previously buffereddata packets to a station even after the station has indicated a futuretransition to a power save state, so that such packets do not have to bere-fetched and re-buffered when the station exits the power save state.Reducing the number of packets that are re-fetched and re-buffered mayincrease throughput of the wireless network.

Other aspects, advantages, and features of the present disclosure willbecome apparent after review of the entire application, including thefollowing sections: Brief Description of the Drawings, DetailedDescription, and the Claims.

V. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a particular illustrative embodiment of a networkconfiguration for communicating data between one or more stations and anaccess point;

FIG. 2 is a diagram of a first illustrative embodiment of data framesthat may be sent between a station and an access point using a definedfetch time between an initial request for buffered traffic and thedelivery of the buffered traffic;

FIG. 3 is a diagram of a second illustrative embodiment of data framesthat may be sent between a station and an access point using a fetchtrigger frame and a delivery trigger frame;

FIG. 4 is a diagram of a third illustrative embodiment of data framesthat may be sent between a station and an access point using an end ofdata indication frame;

FIG. 5 is a diagram of a fourth illustrative embodiment of data framesthat may be sent between a station and an access point using a mediaaccess control header having an end of service period bit as an end ofdata indication;

FIG. 6 is a diagram of a fifth illustrative embodiment of data framesthat may be sent between a station and an access point using a shortframe that indicates that no data is currently pending for the station;

FIG. 7 is a diagram of a sixth illustrative embodiment of data framesthat may be sent between a station and an access point using a shortframe that indicates that data is currently pending for the station;

FIG. 8 is a diagram of a seventh illustrative embodiment of data framesthat may be sent between a station and an access point using a shortframe that indicates that data is currently pending for the station;

FIG. 9 is a flow diagram of a first illustrative embodiment of a methodof communication between a station and an access point;

FIG. 10 is a flow diagram of a second illustrative embodiment of amethod of communication between a station and an access point;

FIG. 11 is a flow diagram of a third illustrative embodiment of a methodof communication between a station and an access point;

FIG. 12 is a flow diagram of a fourth illustrative embodiment of amethod of communication between a station and an access point;

FIG. 13 is a block diagram of a wireless device operable to enter apower saving mode.

VI. DETAILED DESCRIPTION

Referring to FIG. 1, a particular embodiment of a network configurationfor communicating data between one or more stations and an access pointis depicted and generally designated 100. The network configuration 100includes an access point 102 coupled to a network 104. The access point102 may be configured to provide wireless communications to variouscommunication devices such as wireless devices (e.g., stations 106, 108,110). The access point 102 may be a base station. The stations 106, 108,110 may be a personal computer (PC), a laptop computer, a tabletcomputer, a mobile phone, a personal digital assistant (PDA), and/or anydevice configured for wirelessly sending and/or receiving data, or anycombination thereof. The network 104 may include a distributed computernetwork, such as a transmission control protocol/internet protocol(TCP/IP) network.

The access point 102 may be configured to provide a variety of wirelesscommunications services, including but not limited to: Wireless Fidelity(WIFI) services, Worldwide Interoperability for Microwave Access (WiMAX)services, and wireless session initiation protocol (SIP) services. Thestations 106, 108, 110 may be configured for wireless communications(including, but not limited to communications in compliance with the802.11, 802.11-2007, and 802.11x family of specifications developed bythe Institute of Electrical and Electronics Engineers (IEEE)). Inaddition, the stations 106, 108, 110 may be configured to send data toand receive data from the access point 102. In an illustrativeembodiment, the access point 102 and the stations 106-110 maycommunicate via a sub-1 GHz wireless network (e.g., a wireless networkconfigured in accordance with an IEEE 802.11ah specification, standard,and/or protocol).

The stations 106, 108, 110 may be configured to enter a power save modeto conserve power and extend battery life when operating in a mode thatdoes not involve sending data to or receiving data from the access point102. For example, the power save mode may be entered by a station eitherupon initiation by a user or after expiration of a period of sufficientinactivity. In the power save mode, the amount of power consumed by thestation is reduced as compared to the amount of power used during normaloperation. While a particular station is in the power save mode, theaccess point 102 buffers data intended for delivery to the particularstation. However, problems may arise in determining when the stationsshould resume normal operation from the power save mode to send andreceive communications data.

For example, it may take the access point 102 considerable time toretrieve the buffered data. During this time, a particular stationtypically waits for the access point 102 to retrieve the buffered dataand stays in the “wake” state, which consumes power. One solution may beto introduce a defined fetch time between an initial request forbuffered traffic and the earliest delivery of the buffered traffic sothat the station may “sleep” during the defined fetch time, therebyconserving power.

Referring to FIG. 2, a first illustrative embodiment of data frames thatmay be sent between a station, such as one or more of the stations 106,108, 110 of FIG. 1, and an access point, such as the access point 102 ofFIG. 1, using a defined fetch time between an initial request forbuffered traffic (at a first time) and the delivery of the bufferedtraffic (at a second time), is depicted and generally designated 200.The data frames include a fetch trigger frame 202, a firstacknowledgement (ACK) frame 204, a data frame 206, and a second ACKframe 208. A fetch time 210, a first short interframe space (SIFS) 212,a second SIFS 214, and a channel access 216 are associated withtransmissions of the data frames 200.

In a particular embodiment, the fetch time 210 can be timed off of thefetch trigger frame 202, which triggers the access point 102 to fetchthe buffered data. In a particular embodiment, the fetch trigger frame202 may be a power save poll (PS-Poll) frame or an unscheduledasynchronous power save delivery (U-APSD) trigger frame that may bemodified to include the fetch time 210. For example, the fetch time 210may be included in the fetch trigger frame 202, included in a response(e.g., the ACK frame 204) to the fetch trigger frame 202, or advertisedby the access point 102 in a beacon or other frame directed at aparticular station. After the receipt of the fetch trigger frame 202,the access point 102 does not send the fetched data to the station untilafter the end of the fetch time 210.

To illustrate, one of the stations 106, 108, 110, such as the station106, may send a request for data buffered at the access point 102. Itshould be noted that the station 106 is used for example only, and thatthe communications illustrated in FIGS. 2-6 may occur with respect toany of the stations 106-110 or other stations not shown. Fetching thebuffered data may start once the access point 102 receives the fetchtrigger frame 202. The ACK frame 204 may be sent by the access point 102to the station 106 to acknowledge receipt of the fetch trigger frame202. The delivery of the fetched data from the access point 102 to thestation 106 may start after a known delay, such as the fetch time 210,after receipt of the fetch trigger frame 202. The station 106 may entera power save mode (e.g. a sleep mode) during the known delay or fetchtime 210, and only needs to be awake (e.g., transition from the sleepmode to an operating mode) when the fetched data is delivered or readyto be delivered. The fetch time may be timed based on the ACK frame 204or on the fetch trigger frame 202.

For example, the station 106 may send the fetch trigger frame 202 to theaccess point 102. The access point 102 may fetch buffered data duringthe fetch time 210. Frames may be sent by the access point 102 to theother stations 108, 110 during the fetch time 210, but not to thestation 106. The station 106 may “sleep” during the fetch time 210(e.g., until a determination at the station 106 that the fetch time haselapsed, such as upon expiration of a timer at the station 106). Theaccess point 102 may refrain from transmitting the fetched data to thestation 106 until determining, at the access point 102, that the fetchtime 210 has elapsed. For example, the access point 102 may measure thefetch time 210 using a timer and may refrain from transmitting thefetched data to the station 106 until the timer expires. Alternately,the access point 102 may refrain from transmitting the fetched data tothe station 106 until a delivery trigger frame is received, as furtherdescribed with reference to FIG. 3. However, in contrast to networkallocation vector (NAV)-based mechanisms that prevent communication byany device during the NAV time period, the access point 102 may have theability to communicate with other stations during the fetch time 210.For example, the access point 102 may send and receive data framesand/or control frames from other associated stations during the fetchtime 210. After the fetch time 210 (and after a time 216 for channelaccess), the data frame 206 may be sent by the access point 102 to thestation 106. The channel access time 216 may coincide with the end ofthe fetch time 210. End of service period (EOSP) signaling may be usedto indicate that no further traffic is buffered at the access point 102and that the station 106 can go back to the sleep state. For example, anEOSP bit having a value of “1” may be included in a media access control(MAC) header of the data frame 206, indicating that no further trafficis buffered at the access point 102. After receiving the data frame 206from the access point 102, the station 106 may send the second ACK frame208 to the access point 102 to acknowledge receipt of the data frame206. The station 106 may sleep after receipt of the data frame 206.

Referring to FIG. 3, a second illustrative embodiment of data framesthat may be sent between a station, such as one or more of the stations106, 108, 110 of FIG. 1, and an access point, such as the access point102 of FIG. 1, using a fetch trigger frame and a delivery trigger frameto define a fetch time between an initial request for buffered trafficand the delivery of the buffered traffic, are depicted and generallydesignated 300. The data frames 300 include a fetch trigger frame 302, afirst acknowledgement (ACK) frame 304, a delivery trigger frame 306, asecond ACK frame 308, a data frame 310, and a third ACK frame 312. Afetch time 314, a first short interframe space (SIFS) 316, a second SIFS318, a first channel access 320, and a second channel access 322 areassociated with transmissions of the data frames 300.

In a particular embodiment, the access point 102 starts to fetch databuffered at the access point 102 after receiving the fetch trigger frame302 from a particular station, such as the station 106. The access point102 may refrain from transmitting the fetched data to the station 106until determining that the delivery trigger frame 306 has been receivedfrom the station 106. However, in contrast to network allocation vector(NAV)-based mechanisms that prevent communication by any device duringthe NAV time period, the access point 102 may have the ability tocommunicate with other stations during the fetch time 210. The accesspoint 102 delivers the fetched data to the station 106 after receivingthe delivery trigger frame 306 from the station 106. The station 106stays awake after sending the delivery trigger frame 306 until thestation 106 receives the data frame 310 from the access point 102.

The delivery trigger frame 306 may be a newly defined frame, anunscheduled asynchronous power save delivery (U-APSD) trigger frame, ora power save poll (PS-Poll) frame. The fetch trigger frame 302 may be anewly defined frame, an unscheduled asynchronous power save delivery(U-APSD) trigger frame, or a power save poll (PS-Poll) frame. The fetchor delivery trigger aspect may be signaled through fields in existingframes.

A reset interval may be defined beyond which the fetched data isreturned to the access point's power save buffer, when no deliverytrigger frame is received.

A minimum fetch time may be indicated by the access point 102, in abeacon, a probe response, an association response, or in a specificaction frame. The actual fetch time may be programmed at the accesspoint or by the particular station. To illustrate, the station 106 maysend a request for data buffered at the access point 102. Fetching thebuffered data may start after the access point 102 receives the fetchtrigger frame 302. The ACK frame 304 may be sent by the access point 102to the station 106 to acknowledge receipt of the fetch trigger frame302. The delivery of the fetched data from the access point 102 to thestation 106 starts after receipt by the access point 102 of the deliverytrigger 306 from the station 106. The second ACK frame 308 may be sentby the access point 102 to the station 106 to acknowledge receipt of thedelivery trigger 306. The station 106 stays awake after sending thedelivery trigger 306 to the access point 102 until the station 106receives the data frame 310 from the access point 102.

For example, the station 106 may send the fetch trigger frame 302 to theaccess point 102. The access point 102 may fetch data that is bufferedat the access point 102 during the fetch time 314 after receipt of thedelivery trigger 306. Frames may be sent by the access point 102 to theother stations 108, 110 during the fetch time 314 but not to the station106. The station 106 may “sleep” during the fetch time 314, therebysaving power. The data frame 310 may be sent by the access point 102 tothe station 106 after the access point 102 receives the delivery trigger306. An end of service period (EOSP) signaling may be used to indicatethat no further traffic is buffered at the access point 102 and that thestation 106 can go back to the sleep state. After receiving the dataframe 310, the station 106 may send the third ACK frame 312 to theaccess point 102 to acknowledge receipt of the data frame 310. Thestation 106 may sleep after receiving the data frame 310 (e.g., upondetection of the EOSP).

Thus, as illustrated with reference to FIGS. 2-3, an access point mayrefrain from transmitting data frames to a station until a deliverycondition is satisfied. The delivery condition may be satisfied uponexpiration of the predetermined fetch time 210 of FIG. 2 or upon receiptof the delivery trigger packet 306 of FIG. 3. Similarly, the station maynot exit a power save mode until a wake condition is satisfied. The wakecondition may be satisfied upon expiration of the predetermined fetchtime 210 of FIG. 2 or the fetch time 314 prior to transmission of thedelivery trigger packet 306 of FIG. 3.

Referring to FIG. 4, a third illustrative embodiment of data frames thatmay be sent between a station, such as one or more of the stations 106,108, 110 of FIG. 1, and an access point, such as the access point 102 ofFIG. 1, using an end of data indication frame, is depicted and generallydesignated 400. The data frames 400 include a power management frame 402including a power management bit, a first acknowledgement (ACK) frame404, a data frame 406, a second ACK frame 408, an end of data indication(EODI) frame 410, and a third ACK frame 412. A first short interframespace (SIFS) 414, a second SIFS 416, a third SIFS 418, a first channelaccess 420, and a second channel access 422 are associated withtransmissions of the data frames 400.

The access point 102 may discard several pending frames for a particularstation, such as the station 106, when the particular station enters apower save mode because the access point 102 may have scheduled suchframes for transmission and may not have the capability to pull themback from a transmission queue and store them as buffered frames.

In a particular embodiment, the EODI frame 410 may be scheduled fortransmission by the access point 102 when the station 106 is to enter apower save mode. After scheduling the EODI frame 410, the access point102 may buffer further traffic destined for the station 106 so that theEODI frame 410 is the last frame sent to the station 106 after itentered the power save mode. The station 106 may refrain from enteringthe power save mode (e.g., may delay going to sleep) after indicatingits pending transition to the power save mode until the station receivesthe EODI frame 410.

For example, the station 106 may indicate that it is to enter the powersave mode by sending the power management frame 402 to the access point102. For example, the power management (PM) bit may have a value of “1”to indicate that the station 106 is to enter the power save mode. The PMbit on a prior frame sent by the station 106 to the access point 102 mayhave had a value of 0, indicating that the station 106 was in activemode. In response to receiving the power management frame 402, theaccess point 102 may schedule the EODI frame 410 for the station 106.The first ACK frame 404 may be sent by the access point 102 to thestation 106 to acknowledge receipt of the power management frame 402. Asexplained above, the access point 102 continues to send data which hadalready been prepared for transmission at the time the power managementframe 402 is received from the station 106, and the station 106continues to remain awake and receive the data from the access point102. To illustrate, the access point 102 continues to send the data,such as the data frame 406, to the station 106. The station 106 staysawake and receives the data until it receives the EODI frame 410 fromthe access point 102. The second ACK frame 408 may be sent by thestation 106 to the access point 102 to acknowledge receipt by thestation 106 of the data frame 406. The third ACK frame 412 may be sentby the station 106 to the access point 102 to acknowledge receipt of theEODI frame 410. The station 106 may sleep after receiving the EODI frame410. The access point 102 sends no data to the station 106 after theaccess point 102 sends the EODI frame 410 to the station 106.

Alternatively, the end of data indication may be a bit inside the mediaaccess control (MAC) header. For example, the end of data indication maybe an end of service period (EOSP) bit, and the access point 102 may setthe EOSP bit=1 on a final frame sent to a particular station after theparticular station indicates a transition to the power save mode. Thus,the frame that is used to enter power save mode may also trigger aservice period that is terminated with a frame with the EOSP bit set to1.

For example, referring to FIG. 5, a fourth illustrative embodiment ofdata frames that may be sent between a station, such as one or more ofthe stations 106, 108, 110 of FIG. 1, and an access point, such as theaccess point 102 of FIG. 1, using a bit inside a media access controlheader as an end of data indication, is depicted and generallydesignated 500. The data frames 500 include a power management frame 502including a power management bit, a first acknowledgement (ACK) frame504, a first data frame 506 including an end of service period (EOSP)bit, a second ACK frame 508, a second data frame 510 including an end ofservice period (EOSP) bit, and a third ACK frame 512. A first shortinterframe space (SIFS) 514, a second SIFS 516, a third SIFS 518, afirst channel access 520, and a second channel access 522 are associatedwith transmissions of the data frames 500.

A station, such as the station 106, may enter the power save mode bysending the power management frame 502 to the access point 102. Forexample, a power management (PM) bit within the power management frame502 may have a value of “1” to indicate that the station 106 is enteringthe power save mode. At the time power management frame 502 is sent tothe access point 102, the access point 102 may have queued the dataframe 506 and the data frame 510 for transmission to the station 106.The access point 102 may send the second data frame 510 with the EOSPbit=1 because the second data frame 510 is the final frame to thestation 106. In a particular embodiment, the final frame with the EOSP=1may be a newly scheduled frame that is scheduled in response to theaccess point 102 receiving the power management frame 502 with the PMbit=1, similar to the EODI frame described above. The first ACK frame504 may be sent by the access point 102 to the station 106 toacknowledge receipt of the power management frame 502. As explainedabove, the access point 102 continues to send data that had already beenprepared at the time the power management frame 502 with the PM bit=1 isreceived from the station 106 until access point 102 sends the seconddata frame 510 with the EOSP bit=1.

To illustrate, the access point 102 continues to send data, such as thefirst data frame 506, to the station 106. The station 106 stays awakeuntil it receives the second data frame 510 with the EOSP bit=1 from theaccess point 102. The second ACK frame 508 may be sent by the station106 to the access point 102 to acknowledge receipt of the first dataframe 506 with the EOSP bit=0 (e.g., the EOSP bit=0 indicates that thedata frame is not the final frame to be sent). The third ACK frame 512may be sent by the station 106 to the access point 102 to acknowledgereceipt of the second data frame 510 with the EOSP bit=1. The station106 may sleep after receiving the second data frame 510 with the EOSPbit=1. The access point 102 stops sending data to the station 106 afterthe access point 102 sends the second data frame 510 with the EOSP bit=1to the station 106. Alternatively, in response to the station 106indicating a pending transition to the power save mode by sending thepower management frame 502 with the PM bit=1, the station 106 mayimplicitly start an unscheduled service period, which may be terminatedby the access point 102 sending the second data frame 510 with the EOSPbit=1 to the station 106.

A particular station that is in the power save mode may periodicallycheck for the presence of traffic buffered at an access point by sendinga power save poll (PS-Poll) frame. The access point may respond with anacknowledgement (ACK) frame, followed after some time by a null framethat indicates that no data is pending for the station, in response towhich the station sends an acknowledgement frame. These frame exchangesand the corresponding delay may cause power consumption inefficiency atthe station.

In response to no traffic being buffered at the access point destinedfor the particular station, the access point may respond to the PS-Pollframe with a short frame that indicates that no data is currentlypending for the particular station. The response frame could be an ACKframe in which a more data (MD) bit indicates whether traffic isbuffered for the particular station or not. For example, a value of “1”in the MD bit may indicate that traffic is buffered, and a value of “0”in the MD bit may indicate that no traffic is buffered. Alternatively, avalue of “0” in the MD bit may indicate that traffic is buffered, and avalue of “1” in the MD bit may indicate that no traffic is buffered. Theaccess point may base the determination that traffic is buffered for theparticular station on a traffic indication map (TIM) that is stored in alower portion of the medium access coordinator. The station'sassociation identifier (AID) that is present in the PS-Poll frame mayserve as an offset into the TIM in order to quickly determine whetherbuffered frames are present for the station.

Referring to FIG. 6, a fifth illustrative embodiment of data frames thatmay be sent between a station, such as one or more of the stations 106,108, 110 of FIG. 1, and an access point, such as the access point 102 ofFIG. 1, using a short frame that indicates that no data is currentlypending for the station, is depicted and generally designated 600. Thedata frames 600 include a first power save poll (PS-Poll) frame 602, afirst acknowledgement (ACK) frame 604, a second PS-Poll frame 606, asecond ACK frame 608, a third PS-Poll frame 610, and a third ACK frame612. A first short interframe space (SIFS) 614, a second SIFS 616, athird SIFS 618, a first station sleep time 620, and a second stationsleep time 622 are associated with transmissions of the data frames 600.

In a particular embodiment, the station 106 may periodically send aPS-Poll frame, such as the first PS-Poll frame 602, to the access point102 to check for the presence of buffered traffic at the access point102. In response to no traffic being buffered at the access point 102for the station 106, the access point 102 may respond with the first ACKframe 604. The first ACK frame 604 may indicate whether trafficassociated with the station 106 (e.g., traffic buffered for the station106) is present. For example, as illustrated in FIG. 6, the access point102 may send the first ACK frame 604 with the more data bit=0,indicating that traffic associated with the station is not currentlybuffered at the access point 102. In a particular embodiment, the firstACK frame 604 may be sent after the first SIFS 614 after the firstPS-Poll frame 602. The first SIFS 614 is typically too short a timeframefor the access point 102 to fetch buffered traffic. However, the firstSIFS 614 may be a sufficient timeframe to check whether or not trafficis buffered. Information about the presence of buffered traffic isbroadcast by the access point 102 in a traffic indication map (TIM), andthe information from the TIM can be buffered at a low layer in themedium access coordinator, where a quick check can be performed todetermine whether traffic is pending for the station 106 or not.Alternatively, other bits or fields in the MAC header of a responseframe may be used to indicate the presence of buffered traffic. Thestation 106 may sleep in response to receiving the first ACK frame 604until the second PS-Poll frame 606 is sent.

For example, the station 106 may sleep until sending the second PS-Pollframe 606 to the access point 102 to check for the presence of bufferedtraffic. In response to no traffic being buffered by the access point102 for the station 106, the access point 102 may respond to the secondPS-Poll frame 606 with the second ACK frame 608 with the more data (MD)bit=0. The second ACK frame 608 may be sent after the second SIFS 616after the second PS-Poll frame 606. Alternately, if the station 106receives an ACK frame with MD=1, the station 106 may remain awake toreceive one or more data frames from the access point 102.

To illustrate, referring to FIG. 7, a sixth illustrative embodiment ofdata frames that may be sent between a station, such as one or more ofthe stations 106, 108, 110 of FIG. 1, and an access point, such as theaccess point 102 of FIG. 1, using a short frame that indicates that datais currently pending for the station, is depicted and generallydesignated 700. The data frames 700 include a first power save poll(PS-Poll) frame 702, a first acknowledgement (ACK) frame 704, a dataframe 706, a second ACK frame 708, a second PS-Poll frame 710, and athird ACK frame 712. A first short interframe space (SIFS) 714, a secondSIFS 716, a third SIFS 722, a station wake time 720, and a station sleeptime 724 are associated with transmissions of the data frames 700.

In a particular embodiment, the station 106 may periodically send aPS-Poll frame, such as the first PS-Poll frame 702, to the access point102 to check for the presence of buffered traffic at the access point102. In response to traffic being buffered at the access point 102 forthe station 106, the access point 102 may respond with the first ACKframe 704. The first ACK frame 704 may indicate whether trafficassociated with the station 106 (e.g., traffic buffered for the station106) is present. For example, as illustrated in FIG. 7, the access point102 may send the first ACK frame 704 with the more data bit=1,effectively starting a service period and indicating that trafficassociated with the station is currently buffered at the access point102. In a particular embodiment, the first ACK frame 704 may be sentafter the first SIFS 714 after the first PS-Poll frame 702. The station106 may stay awake until it receives a frame from the access point 102indicating that no further traffic is buffered at the access point 102.For example, end of service period (EOSP) signaling may be used toindicate that no further traffic is buffered at the access point 102 andthat the station 106 can go back to the sleep state. For example, anEOSP bit having a value of “1” may be included in a media access control(MAC) header of the data frame 706, indicating that no further trafficis buffered at the access point 102. After receiving the data frame 706from the access point 102, the station 106 may send the second ACK frame708 to the access point 102 to acknowledge receipt of the data frame706. The station 106 may enter a sleep mode after receipt of the dataframe 706 until the second PS-Poll frame 710 is sent.

For example, the station 106 may sleep until sending the second PS-Pollframe 710 to the access point 102 to check for the presence of bufferedtraffic. In response to no traffic being buffered by the access point102 for the station 106, the access point 102 may respond to the secondPS-Poll frame 710 with the third ACK frame 712 with the more data bit=0.The third ACK frame 712 may be sent after the third SIFS 722 after thesecond PS-Poll frame 710.

In a particular embodiment, to save power, the station 106 may wake uponly to poll the access point 102 to determine whether or not buffereddata is available. However, in this embodiment, the station 106 may missreceiving critical network update information from the access point 102.Such changes may affect an operating mode of a base station systemassociated with the station 106 and the access point 102. For example,the station 106 may be in a power save mode (i.e., sleeping) when theaccess point 102 transmits beacon update information to stations withinrange of the access point 102. To reduce or minimize such scenarios, anacknowledge frame from the access point 102 may include an updatedbeacon version number (BVN) that is used by the station 106 to determinewhether it should wake up to receive a beacon or to solicit a proberesponse by sending a probe request to the access point 102.

To illustrate, referring to FIG. 8, a seventh illustrative embodiment ofdata frames that may be sent between a station, such as one or more ofthe stations 106, 108, 110 of FIG. 1, and an access point, such as theaccess point 102 of FIG. 1, using a short frame that indicates that datais currently pending for the station, is depicted and generallydesignated 800. The data frames 800 include a first power save poll(PS-Poll) frame 802, a first acknowledgement (ACK) frame 804, a firstprobe request frame 806, a second ACK frame 808, a probe response frame810, a third ACK frame 812, a second PS-Poll frame 822, a fourth ACKframe 824, a second probe response frame 826, and a fifth ACK frame 828.A first short interframe space (SIFS) 814, a second SIFS 816, a thirdSIFS 818, a fourth SIFS 830, a fifth SIFS 832, and a wake time 834 areassociated with transmissions of the data frames 800.

In a particular embodiment, the access point 102 updates the beaconversion number when a significant change occurs in the beacon whichneeds to be parsed by all stations in a base station system. Such achange may include a change to channel access parameters through anenhanced distributed channel access parameter set or a change in anoperating bandwidth at the access point 102. To illustrate, the station106 notes that the beacon version number (BVN) has been updated, afterwhich the station 106 solicits a probe response frame by sending a proberequest frame to the access point 102. For example, the station 106 mayperiodically send a PS-Poll frame, such as the first PS-Poll frame 802,to the access point 102 to check for the presence of buffered traffic atthe access point 102. The access point 102 may respond with the firstACK frame 804. The first ACK frame 804 may indicate that the BVN hasbeen updated. For example, as illustrated in FIG. 8, the access point102 may send the first ACK frame 804 including an updated BVN. Inresponse to receiving the first ACK frame 804, the station 106 maysolicit the probe response frame 810 by sending the probe request 806 tothe access point 102. The second ACK frame 808 may be sent by the accesspoint 102 to the station 106 to acknowledge receipt of the probe request806. The access point 102 may send the probe response 810 to the station106. The third ACK frame 812 may be sent by the station 106 to theaccess point 102 to acknowledge receipt of the probe response 810.

Alternatively, when a significant update occurs, the access point 102may schedule a probe response frame for each station that is known to bein a power save mode during which the station does not receive beacons(i.e., a deep sleep mode). A particular station may indicate to theaccess point 102 that it is in a deep sleep mode. For example, theaccess point 102 may buffer a probe response frame for the particularstation when a critical update occurred. To illustrate, the station 106may send the second PS-Poll frame 822 to the access point 102 to checkfor the presence of buffered data at the access point 102. The accesspoint 102 may respond with the fourth ACK frame 824. The fourth ACKframe 824 may indicate that data is buffered with a more data bitvalue=“1”. Alternatively, a value of “0” in the more data bit mayindicate that data is buffered. The station 106 may stay awake until itreceives a frame from the access point 102 indicating that no furtherdata is buffered at the access point 102. For example, end of serviceperiod (EOSP) signaling may be used to indicate that no further data isbuffered at the access point 102 and that the station 106 can go back toa sleep state. For example, an EOSP bit having a value of “1” may beincluded in a media access control (MAC) header of the second proberesponse frame 826, indicating that no further data is buffered at theaccess point 102. After receiving the second probe response frame 826from the access point 102, the station 106 may send the fifth ACK frame828 to the access point 102 to acknowledge receipt of the second proberesponse frame 826.

The second probe response frame 826 may be encapsulated in a data frameso that an EOSP field is present. The second probe response frame 826may be transmitted using a quality of service (QoS) management framethat includes an EOSP field.

Thus, as described with reference to FIGS. 6-8, when no traffic isbuffered at the access point (AP) destined for the station (STA), the APresponds to the PS-Poll frame with a short frame that indicates that nodata is currently pending for the STA. The response frame could be anACK frame in which the MD bit is defined to indicate whether traffic isbuffered (1) for the STA or not (0).

The signaling of the MD bit may be reversed to let ‘1’ indicate that notraffic is buffered and ‘0’ that traffic may be buffered, which allowsthat the feature is implemented with very little changes to the existingimplementation (in which the STA would stay awake after receiving an ACKframe with MD=0 in response to a PS-Poll frame).

The ACK frame is sent SIFS after the PS-Poll frame. This time istypically too short for an AP to fetch buffered traffic, but a checkwhether traffic buffered is likely easy to meet the timing schedule.Information about the presence of buffered traffic is already broadcastby the AP in the traffic indication map (TIM), and the information fromthe TIM can be buffered at a low layer in the medium access coordinatorwhere a quick check can be performed whether traffic is pending for aSTA or not. As illustrated in FIG. 6, the STA periodically sends aPS-Poll to the AP to check the presence of buffered traffic. When notraffic is buffered for the STA at the AP, the AP responds with an ACKframe in which the MD bit indicates that no data is buffered for theSTA.

Alternatively, other bits or fields in the MAC header of a responseframe may be used to indicate the presence of buffered traffic. Whentraffic is buffered at the AP, the ACK frame from the AP will indicatethat by setting the MD field to 1, effectively starting a serviceperiod. In this case, the STA stays awake until it receives from the APa frame with the EOSP bit set to 1. The service period may effectivelystart after a defined fetch time on behalf of the AP, during which theAP fetches the buffered data and during which the STA may enter a sleepmode. The AP will send no data to the STA during the fetch time. Asillustrated in FIG. 7, the STA periodically sends a PS-Poll to the AP tocheck the presence of buffered traffic. When traffic is buffered for theSTA at the AP, the AP responds with an ACK frame in which the MD bitindicates that data is buffered for the STA, followed by the data. TheAP sets the EOSP field to 1 when the final data frame is sent to theSTA, ending the service period.

The ACK response frame from the AP may include a beacon version number(BVN) that is used by the STA to determine whether it should wake up toreceive a beacon or to solicit a probe response by sending a proberequest to the AP. As illustrated in FIG. 8, the STA notes that thebeacon version number (BVN) has been updated, after which the STAsolicits a probe response frame by sending a probe request frame to theAP.

The AP updates the beacon version number when a significant changeoccurs in the beacon which needs to be parsed by all STAs in the BSS.Such a change may include a change to the channel access parametersthrough the EDCA Parameter Set or a change in the operating bandwidth atthe AP.

Alternatively, when a significant update occurs, AP may schedule a proberesponse frame for each STA that is known to be in a power save modeduring which the STA does not receive beacons (i.e. a deep sleep mode).A STA may indicate to the AP that it is in a deep sleep mode.

The buffered probe response frame may be encapsulated in a data frame sothat an EOSP field is present. The buffered probe response frame may betransmitted using a QoS management frame that includes an EOSP field.

For IEEE 802.11ah associations, the more data (MD) field in managementframes (e.g., the MD field of the frames 604, 608, 612 of FIG. 6, the MDfield of the frames 704, 708, and 712 of FIG. 7, or the MD field of theframe 824 of FIG. 8) may function as an end of service period (EOSP)field. For example, a PS-Poll frame may start an unscheduledasynchronous power save delivery (U-APSD) service period, which mayterminate responsive to a frame with the EOSP field set to 1 (e.g., asillustrated by the frame 206 of FIG. 2, the frame 310 of FIG. 3, theframe 510 of FIG. 5, the frame 706 of FIG. 7, and the frame 826 of FIG.8). Thus, a legacy interpretation in which a PS-Poll frame triggers thetransmission of a single frame may not be present for IEEE 802.11ahassociations.

It will thus be appreciated that various embodiments described hereinmay reduce inefficient use of resources by preventing sleep mode incertain conditions and forcing recognition of sleep mode in otherconditions. For example, when a STA indicates an upcoming transition tosleep mode, the STA may be prevented from entering the sleep mode untilany previously buffered traffic is delivered to the STA and/or until theSTA receives an indication from an AP that no buffered traffic existsfor the STA. In addition, by waiting for a delivery condition to besatisfied (e.g., a fetch time to elapse or a delivery trigger frame tobe received) before transmitting data to the STA, the AP may reduce orminimize retransmissions. It will also be appreciated that in contrastto other power save methods, embodiments described herein may enable aSTA to wake up as desired instead of in accordance with a predeterminedschedule that is shared between the STA and an AP.

Referring to FIG. 9, a particular illustrative embodiment of a method ofcommunication between a station and an access point is depicted andgenerally designated 900. The method 900 may be performed by an accesspoint, such as the access point 102 of FIG. 1.

The method 900 includes receiving a power save polling (PS-Poll) framefrom a station at an access point, at 902. For example, in FIG. 6, thePS-Poll frame 602 may be received by an access point. The method 900also includes, in response to receiving the PS-Poll frame, transmittinga frame from the access point to the station indicating whether trafficassociated with the station is buffered at the access point, at 904. Ina particular embodiment, a more data (MD) bit of an acknowledgement(ACK) frame may be used to represent the indication. For example, inFIG. 6, the ACK frame 604 including the MD bit=0 may be transmitted fromthe access point to the station. The method 900 of FIG. 9 may beperformed multiple times during operation of the station and the accesspoint. For example, additional PS-Poll frames 606, 610 and ACK frames608,612 may be communicated between the station and the access point.

Referring to FIG. 10, a particular illustrative embodiment of a methodof communication between a station and an access point is depicted andgenerally designated 1000. The method 1000 may be performed by astation, such as one or more of the stations 106, 108, 110 of FIG. 1.

The method 1000 includes transmitting a first frame from a station to anaccess point indicating that the station is to enter a power save mode,at 1002. For example, referring to FIGS. 4-5, the station may transmitthe power management (PM) frame 402 of FIG. 4 or the PM frame 502 ofFIG. 5.

The method 1000 also includes refraining from entering the power savemode until an end of data frame is received from the access point, at1004, and entering the power save mode at the station in response toreceiving the end of data frame from the access point, at 1006. Forexample, the end of data frame may be the EODI frame, such as the EODIframe 410 of FIG. 4. Alternately, the end of data frame may include anasserted EOSP bit, as illustrated by the frame 510 of FIG. 5. Refrainingfrom entering the power save mode until the EODI frame or asserted EOSPbit is received may reduce the number of data frames that are re-fetchedand re-buffered, which may reduce power consumption at the access pointand the station and increase throughput between the access point and thestation.

Referring to FIG. 11, a particular illustrative embodiment of a methodof communication between a station and an access point is depicted andgenerally designated 1100. The method 1100 may be performed by an accesspoint, such as the access point 102 of FIG. 1.

The method 1100 includes receiving a fetch trigger frame from a stationat an access point, at 1102. For example, referring to FIGS. 2-3, thefetch trigger frame 202 of FIG. 2 or the fetch trigger frame 302 of FIG.3 may be received at an access point.

The method 1100 also includes fetching one or more data framesassociated with the station in response to the fetch trigger frame, at1104. For example, referring to FIGS. 2-3, the data frame 206 of FIG. 2or the data frame 310 of FIG. 3 may be fetched (i.e., prepared fordelivery) by the access point.

The method 1100 further includes refraining from transmitting the one ormore fetched data frames to the station until a delivery condition issatisfied, at 1106. For example, the delivery condition may be satisfiedwhen a predetermined time period, such as the fetch time 210 of FIG. 2(during which the station may enter a power save mode) has elapsed.Alternately, the delivery condition may be satisfied when a deliverytrigger frame is received from the station, such as the delivery triggerframe 306 of FIG. 3. Refraining from transmitting the data frames untilthe delivery condition is satisfied may prevent the access pointtransmitting data to the station while the station is in a power savemode (e.g. asleep).

Referring to FIG. 12, a particular illustrative embodiment of a methodof communication between a station and an access point is depicted andgenerally designated 1200. The method 1200 may be performed by an accesspoint, such as the access point 102 of FIG. 1.

The method 1200 includes receiving a power save polling (PS-Poll) framefrom a station at an access point, at 1202. For example, in FIG. 7, thePS-Poll frame 702 may be received by an access point. In a particularembodiment, the method 1200 may include, in response to receiving thePS-Poll frame, transmitting a frame from the access point to the stationindicating that traffic associated with the station is buffered at theaccess point, at 1204. For example, the frame may include an updatedbeacon version number and may be sent to prevent the station fromsleeping before receiving the updated beacon version number. Toillustrate, the frame with the updated beacon version number may be theframe 804 of FIG. 8. The method 1200 may further include receiving aprobe request frame from the station at the access point, at 1206, andtransmitting a probe response frame to the station from the accesspoint, at 1208. For example, the probe request frame may be the proberequest frame 806 of FIG. 8 and the probe response frame may be theprobe response frame 810 of FIG. 8.

In an alternate embodiment, the method 1200 may include scheduling aprobe response frame for stations that are known to be in power savemode (e.g., sleeping). The scheduled probe response frame may betransmitted using a quality of service (QoS) management frame having anEOSP bit=1. For example, the method 1200 may include transmitting aframe from the access point to the station indicating that trafficassociated with the station is buffered (to prevent the station fromsleeping), at 1210, and scheduling a probe response frame fortransmission to the station, at 1212. To illustrate, the probe responseframe may be the probe response frame 826 of FIG. 8, having the EOSPbit=1.

The methods of FIGS. 9-12 may thus reduce power consumption and increasesignaling efficiency between stations and access points in a wirelessnetwork. The methods of FIGS. 9-12 may also reduce the number of packetsthat are re-fetched and re-buffered, which may increase throughput ofthe wireless network.

Referring to FIG. 13, a block diagram of a particular illustrativeembodiment of a wireless electronic device is depicted and generallydesignated 1300. In an illustrative embodiment, one or more componentsof the wireless electronic device 1300 may be included in an accesspoint (e.g., the access point 102 of FIG. 1) or a station (e.g., thestations 106-110 of FIG. 1). All or part of the one or more of methodsdescribed in FIGS. 9-12 may be performed at the wireless electronicdevice 1300 of FIG. 13. The wireless electronic device 1300 includes aprocessor 1310, such as a digital signal processor (DSP), coupled to amemory 1332.

The memory 1332 is a non-transitory tangible computer readable storagemedium that stores instructions 1360. The instructions 1360 may beexecutable by the processor 1310. For example, the instructions 1360 mayinclude instructions to initiate, control, and/or perform one or more ofthe methods or functions described herein, such as the methods 900-1200of FIGS. 9-12 and/or variations or portions thereof. In a particularembodiment, the memory 1332 stores PS-Poll frames, Power Managementframes, fetch trigger frames and/or delivery trigger frames or messages,as described with reference to FIGS. 2-6. Alternatively, the frames ormessages may be stored at the network and retrieved in response toreceiving a request for buffered data from the wireless electronicdevice 1300. For example, the wireless electronic device 1300 may be anyof the stations 106-110 (or a component of any station) of FIG. 1.

FIG. 13 also shows a display controller 1326 that is coupled to theprocessor 1310 and to a display device 1328. A coder/decoder (CODEC)1334 can also be coupled to the processor 1310. A speaker 1336 and amicrophone 1338 can be coupled to the CODEC 1334. FIG. 13 also indicatesthat a wireless controller 1340 can be coupled to the processor 1310 andto a wireless antenna 1342. In a particular embodiment, the processor1310, the display controller 1326, the memory 1332, the CODEC 1334, andthe wireless controller 1340 are included in a system-in-package orsystem-on-chip device 1322. In a particular embodiment, an input device1330 and a power supply 1344 are coupled to the system-on-chip device1322. Moreover, in a particular embodiment, as illustrated in FIG. 13,the display device 1328, the input device 1330, the speaker 1336, themicrophone 1338, the wireless antenna 1342, and the power supply 1344are external to the system-on-chip device 1322. However, each of thedisplay device 1328, the input device 1330, the speaker 1336, themicrophone 1338, the wireless antenna 1342, and the power supply 1344can be coupled to a component of the system-on-chip device 1322, such asan interface or a controller.

In conjunction with the described embodiments, a first apparatusincludes means for receiving a fetch trigger frame from a station at anaccess point. For example, the means for receiving may include theprocessor 1310, the wireless controller 1340, the wireless antenna 1342,one or more other devices configured to receive data, or any combinationthereof. The apparatus also includes means for fetching, in response tothe fetch trigger frame, one or more data frames associated with thestation. For example, the means for fetching may include the processor1310, the memory 1332, one or more other devices configured to fetchdata, or any combination thereof. The apparatus further includes meansfor refraining from transmitting the one or more fetched data frames tothe station until determining at the access point that a fetch timeassociated with the station has elapsed or until a delivery triggerframe is received from the station. The access point is configured tocommunicate with one or more other stations during the fetch time. Forexample, the means for refraining may include the processor 1310, thewireless controller 1340, one or more other devices configured torefrain from transmitting data, or any combination thereof.

A second apparatus includes means for transmitting a fetch trigger framefrom a station to an access point. For example, the means fortransmitting may include the processor 1310, the wireless controller1340, the wireless antenna 1342, one or more other devices configured totransmit data, or any combination thereof. The apparatus also includesmeans for entering a power save mode at the station until adetermination at the station that a fetch time associated with thestation has elapsed and for exiting the power save mode in response tothe determination. The access point is configured to communicate withone or more other stations during the fetch time. For example, the meansfor entering and for exiting may include the processor 1310, thewireless controller 1340, one or more other devices configured to enterand exit power save mode, or any combination thereof. The apparatusfurther includes means for receiving one or more data frames from theaccess point at the station after exiting the power save mode. Forexample, the means for receiving may include the processor 1310, thewireless controller 1340, the wireless antenna 1342, one or more otherdevices configured to receive data, or any combination thereof.

A third apparatus includes means for receiving a first frame from astation at an access point, the first frame indicating that the stationis to enter a power save mode. For example, the means for receiving mayinclude the processor 1310, the wireless controller 1340, the wirelessantenna 1342, one or more other devices configured to receive data, orany combination thereof. The apparatus also includes means fortransmitting one or more data frames and an end of data frame from theaccess point to the station. The one or more data frames were bufferedfor transmission prior to receipt of the first frame. For example, themeans for transmitting may include the processor 1310, the wirelesscontroller 1340, the wireless antenna 1342, one or more other devicesconfigured to transmit data, or any combination thereof.

A fourth apparatus includes means for transmitting a first frame from astation to an access point, the first frame indicating that the stationis to enter a power save mode. For example, the means for transmittingmay include the processor 1310, the wireless controller 1340, thewireless antenna 1342, one or more other devices configured to transmitdata, or any combination thereof. The apparatus also includes means forrefraining from entering the power save mode until an end of data frameis received from the access point. For example, the means for refrainingmay include the processor 1310, the wireless controller 1340, one ormore other devices configured to refrain from entering power save mode,or any combination thereof. The apparatus further includes means forentering the power save mode at the station in response to receiving theend of data frame from the access point. For example, the means forentering may include the processor 1310, the wireless controller 1340,one or more other devices configured to enter a power save mode, or anycombination thereof.

A fifth apparatus includes means for receiving a power save pollingframe from a station at an access point. For example, the means forreceiving may include the processor 1310, the wireless controller 1340,the wireless antenna 1342, one or more other devices configured toreceive data, or any combination thereof. The apparatus also includesmeans for transmitting, in response to receipt of the power save pollingframe, a frame from the access point to the station. The frame indicateswhether traffic associated with the station is buffered at the accesspoint. For example, the means for transmitting may include the processor1310, the wireless controller 1340, the wireless antenna 1342, one ormore other devices configured to transmit data, or any combinationthereof.

A sixth apparatus includes means for transmitting a power save pollingframe from a station to an access point. For example, the means fortransmitting may include the processor 1310, the wireless controller1340, the wireless antenna 1342, one or more other devices configured totransmit data, or any combination thereof. The apparatus also includesmeans for receiving, in response to transmitting the power save pollingframe, a frame from the access point indicating whether trafficassociated with the station is buffered at the access point. Forexample, the means for receiving may include the processor 1310, thewireless controller 1340, the wireless antenna 1342, one or more otherdevices configured to receive data, or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, configurations, modules, circuits, and algorithm stepsdescribed in connection with the embodiments disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. Various illustrative components, blocks, configurations,modules, circuits, and steps have been described above generally interms of their functionality. Whether such functionality is implementedas hardware or software depends upon the particular application anddesign constraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentdisclosure.

The steps of a method or algorithm described in connection with theembodiments disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in random access memory (RAM), flashmemory, read-only memory (ROM), programmable read-only memory (PROM),erasable programmable read-only memory (EPROM), electrically erasableprogrammable read-only memory (EEPROM), registers, hard disk, aremovable disk, a compact disc read-only memory (CD-ROM), or any otherform of non-transitory storage medium known in the art. An exemplarystorage medium is coupled to the processor such that the processor canread information from, and write information to, the storage medium. Inthe alternative, the storage medium may be integral to the processor.The processor and the storage medium may reside in anapplication-specific integrated circuit (ASIC). The ASIC may reside in acomputing device or a user terminal. In the alternative, the processorand the storage medium may reside as discrete components in a computingdevice or user terminal.

The previous description of the disclosed embodiments is provided toenable a person skilled in the art to make or use the disclosedembodiments. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the principles defined hereinmay be applied to other embodiments without departing from the scope ofthe disclosure. Thus, the present disclosure is not intended to belimited to the embodiments disclosed herein but is to be accorded thewidest scope possible consistent with the principles and novel featuresas defined by the following claims.

What is claimed is:
 1. A method comprising: buffering, by an access point, data for a first station; receiving, by the access point, a first frame from the first station after buffering the data, the first frame including a trigger frame indicating that the first station is to enter and exit a power save mode; transmitting, by the access point, one or both of an acknowledgment indicating receipt of the first frame and an indication of a fetch time period to the first station, an end of the fetch time period indicating one or both of exiting the power save mode and starting a service period of the access point; and transmitting, by the access point, one or more frames to one or more other stations but not to the first station during the fetch time period after receiving the first frame.
 2. The method of claim 1, wherein transmitting the indication includes sending, from the access point to the first station, information indicating the fetch time period.
 3. The method of claim 1, further comprising, after expiration of the fetch time period, transmitting one or more data frames from the access point to the first station, at least one of the one or more data frames indicating an end of the service period.
 4. The method of claim 1, wherein the first frame comprises a power save poll (PS-poll) frame or an unscheduled asynchronous power save delivery (U-APSD) frame.
 5. The method of claim 1, wherein the buffered data includes data for one or more data frames buffered at the access point while the first station is in the power save mode, the method further comprising fetching the buffered data corresponding to the one or more data frames during the fetch time period and transmitting the one or more data frames to the first station after the fetch time period.
 6. The method of claim 1, wherein the first frame includes information indicating the fetch time period.
 7. A method comprising: after transitioning from a power save mode, transmitting, by a station, a first frame to an access point, the first frame including a trigger frame indicating that the station is to enter and exit the power save mode; receiving at the station from the access point one or both of an acknowledgment indicating receipt of the first frame and an indication of a fetch time period, an end of the fetch time period indicating one or both of exiting the power save mode and starting a service period of the access point; and receiving at the station one or more data frames from the access point after the first frame during the service period but not during the fetch time period.
 8. The method of claim 7, further comprising receiving, at the station from the access point, information indicating the fetch time period.
 9. The method of claim 7, wherein at least one of the one or more data frames indicates an end of the service period.
 10. The method of claim 7, wherein the first frame comprises a power save poll (PS-poll) frame or an unscheduled asynchronous power save delivery (U-APSD) frame, and wherein the one or more data frames include data buffered at the access point while the station is in the power save mode.
 11. The method of claim 7, wherein the first frame includes information indicating the fetch time period.
 12. An apparatus comprising: a processor; and a memory storing instructions executable by the processor to perform operations comprising: buffering, by an access point, data for a first station; receiving, by the access point, a first frame from the first station after buffering the data, the first frame including a trigger frame indicating that the first station is to enter and exit a power save mode; transmitting one or both of an acknowledgment indicating receipt of the first frame and an indication of a fetch time period to the first station, an end of the fetch time period indicating one or both of the exit from the power save mode and a start time of a service period of the access point; and transmitting, by the access point, one or more frames to one or more other stations but not to the first station during the fetch time period after receipt of the first frame.
 13. The apparatus of claim 12, wherein the operations further comprise: sending, from the access point to the first station, information indicating the fetch time period; and after expiration of the fetch time period, transmitting one or more data frames from the access point to the first station, at least one of the one or more data frames indicating an end of the service period.
 14. The apparatus of claim 12, wherein the first frame comprises a power save poll (PS-poll) frame or an unscheduled asynchronous power save delivery (U-APSD) frame.
 15. The apparatus of claim 12, wherein the buffered data includes data for one or more data frames buffered at the access point while the first station is in the power save mode, and wherein the operations further comprise fetching data corresponding to the one or more data frames during the fetch time period.
 16. A non-transitory computer-readable medium comprising instructions that, when executed by a computer, cause the computer to perform operations comprising: buffering, by an access point, data for a first station; receiving a first frame from the first station after buffering the data, the first frame including a trigger frame indicating that the first station is to enter and exit a power save mode; transmitting one or both of an acknowledgment and an indication of a fetch time period to the first station, an end of the fetch time period indicating one or both of exiting the power save mode and starting a service period of the access point; and transmitting, by the access point, one or more frames to one or more other stations but not to the first station during the fetch time period after receiving the first frame.
 17. The non-transitory computer-readable medium of claim 16, wherein the operations further comprise sending, from the access point to the first station, information indicating the fetch time period.
 18. The non-transitory computer-readable medium of claim 16, wherein the first frame comprises a power save poll (PS-poll) frame or an unscheduled asynchronous power save delivery (U-APSD) frame.
 19. An apparatus comprising: means for receiving a first frame from a first station at an access point after buffering data for the first station at the access point, the first frame including a trigger frame indicating that the first station is to enter and exit a power save mode; and means for transmitting one or both of an acknowledgment indicating receipt of the first frame and an indication of a fetch time period to the first station, an end of the fetch time period indicating one or both of the exit from the power save mode and a start time of a service period of the access point, and for transmitting one or more frames to one or more other stations but not to the first station during the fetch time period after receipt of the first frame.
 20. The apparatus of claim 19, wherein the means for transmitting is configured to send, from the access point to the first station, information indicating the fetch time period.
 21. The apparatus of claim 19, wherein the first frame comprises a power save poll (PS-poll) frame or an unscheduled asynchronous power save delivery (U-APSD) frame.
 22. An apparatus comprising: a processor; and a memory storing instructions executable by the processor to perform operations comprising: after a transition of a station from a power save mode, transmitting, by the station, a first frame to an access point, the first frame including a trigger frame indicating that the station is to enter and exit the power save mode; receiving at the station from the access point one or both of an acknowledgment indicating receipt of the first frame and an indication of a fetch time period, an end of the fetch time period indicating one or both of the exit from the power save mode and a start time of a service period of the access point; and receiving at the station one or more data frames from the access point after the first frame during the service period but not during the fetch time period.
 23. The apparatus of claim 22, wherein the operations further comprise receiving, at the station from the access point, information indicating the fetch time period.
 24. The apparatus of claim 22, wherein the first frame comprises a fetch trigger frame or a power save poll (PS-poll) frame.
 25. A non-transitory computer-readable medium comprising instructions that, when executed by a computer, cause the computer to perform operations comprising: after transitioning from a power save mode, transmitting, by a station, a first frame from the station to an access point, the first frame including a trigger frame indicating that the station is to enter and exit the power save mode; in response to transmitting the first frame, receiving at the station from the access point one or both of an acknowledgment and an indication of a fetch time period, an end of the fetch time period indicating one or both of exiting the power save mode and starting a service period of the access point; and receiving at the station one or more data frames from the access point after the first frame during the service period but not during the fetch time period.
 26. The non-transitory computer-readable medium of claim 25, wherein the operations further comprise receiving, at the station from the access point, information indicating the fetch time period.
 27. The non-transitory computer-readable medium of claim 25, wherein the first frame comprises a power save poll (PS-poll) frame or an unscheduled asynchronous power save delivery (U-APSD) frame.
 28. An apparatus comprising: means for transmitting a first frame from a station to an access point after a transition of the station from a power save mode, the first frame including a trigger frame indicating that the station is to enter and exit the power save mode; and means for receiving at the station from the access point one or both of an acknowledgment and an indication of a fetch time period in response to transmitting the first frame, an end of the fetch time period indicating one or both of the exit from the power save mode and a start time of a service period of the access point; and means for receiving at the station one or more data frames from the access point after the first frame during the service period but not during the fetch time period.
 29. The apparatus of claim 28, wherein means for receiving is configured to receive, from the access point, information indicating the fetch time period.
 30. The apparatus of claim 28, wherein the first frame comprises a fetch trigger frame, a power save poll (PS-poll) frame, or an unscheduled asynchronous power save delivery (U-APSD) frame. 